1. Field of the Invention
The present invention relates to a method for measuring blood flow in the bone after a fracture, typically a femoral neck fracture, wherein a hole is drilled into the bone, preferably through the neck of the femur into the head of the femur. The invention also relates to a device for measuring blood flow in the bone after a fracture, typically a femoral neck fracture.
2. Description of the Related Art
All publications herein are incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Often the circulation of the bone, mainly the femoral head is destroyed at a dislocated bone fracture, typically at a femoral neck fracture. If there is inadequate circulation, a necrosis of the femoral head will develop and prosthesis implantation is the most likely course of treatment. Inadequate blood flow in the neck of the femur may lead to inadequate healing of the femoral head after a fracture, as well as cause osteonecrosis, a disease that results from loss of blood supply to the bone where the bone tissue dies and may eventually collapse. If a bone involved in osteonecrosis is near a joint, such as in the case of the femoral head, it often leads to the collapse of the joint surface. Conversely, if there is adequate circulation of the femoral head, the femoral head remains alive and in this way the fracture is capable of healing. In this instance, the most likely surgical solution is to perform osteosynthesis. Thus, the determination of whether there is adequate circulation is an important step in the overall treatment regimen.
Presently, the two most widely used methods for evaluating circulation are angiographic and isotopic methods. However, neither method is effective as the isotope or contrast material flows out of the head of the femur and into the fracture gap. Because the material covers the site to be examined, the examination can only be performed two weeks after the neck fracture. Abnormal blood flow patterns in the bone within a few weeks of a fracture may provide early warning of delayed union or nonunion of the fracture (Ashroft, et al.; “Measurement of Blood Flow in Tibial Fracture Patients Using Positron Emission Tomography,” J Bone Joint Surg [Br] 1992; 74-8:673-677).
A method for measuring blood flow in the bone before surgery will impact treatment selection, which will likely result in improvement of clinical outcome, minimization of cost and prevention of long term disability (Research Study, “Fracture healing—measuring blood in bone using MRI.” Department of Orthopaedics, MEMO, Department of Clinical Radiology at Bristol Infirmary, and Department of Cardiovascular Medicine, John Radcliffe, Oxford). Furthermore, accurate measurement of blood flow is important for orthopaedic research due to close correlation of the flow with bone formation and mineral deposition. Accurate measurements may also allow secondary predictions of bone activity in other bone disoeders.
Bone imaging techniques, including scintigraphy and magnetic resonance imaging, have also been employed by some investigators to determine the blood supply available to the femoral head prior to surgery, these techniques have not been successful.
Watanabe Y, Terashima Y, Takenaka N, Kobayashi M and Matsushita T suggested to measure the intramedullary oxygen tension of the proximal femur after a femoral neck fracture and to evaluate the usefulness of that monitoring for prediction of subsequent avascular necrosis (J Orthop Trauma. 2007 August; 21 (7); 456-61).
Cho M R, Lee S W, Shin D K, Kim S K, Kim S Y, Ko S B, Kwun K W used 7.0 mm cannulated screws for fracture fixation to monitor bleeding (J Orthop Trauma. 2007 March; 21(3):158-64).
A 2.0-millimeter drill was used to assess the presence and character of bleeding from the femoral head at open reduction and internal fixation of a femoral neck fracture, according to Gill T J, Sledge J B, Ekkernkamp A, Ganz R (Orthop Trauma. 1998 September-October; 12(7):474-8).
These techniques, however, often do not provide as detailed and accurate information as the intraoperative techniques, which albeit invasive have been preferred and employed recently. A major limitation of the intraoperative invasive techniques, however, is that assessment of vascularity in the femoral head is often not sufficiently quantitative for routine clinical use.
Thus, there is presently a great need for a method and instrument that can give an accurate and more immediate determination of circulation flow.